Differential Diagnosis for Elevated CEA, CA 19-9, and CA 125
Elevations in carcinoembryonic antigen (CEA), cancer antigen 19-9 (CA 19-9), and cancer antigen 125 (CA 125) can be associated with various malignancies. Here's a structured approach to the differential diagnosis:
Single Most Likely Diagnosis
- Colorectal Cancer with Peritoneal Metastasis: This is a common scenario where CEA is elevated due to the colorectal primary, CA 19-9 can be elevated in some cases of colorectal cancer, and CA 125 can be elevated due to peritoneal metastasis. The combination of these markers, especially in the context of clinical findings like abdominal distension or ascites, points towards a colorectal cancer with spread to the peritoneum.
Other Likely Diagnoses
- Pancreatic Cancer: While CA 19-9 is the most commonly associated marker with pancreatic cancer, some pancreatic cancers can also elevate CEA and CA 125, especially if there's peritoneal involvement.
- Ovarian Cancer: Ovarian cancers often elevate CA 125, and some may also elevate CEA and CA 19-9, particularly if there's metastasis to other parts of the abdomen.
- Gastric Cancer: Gastric cancers can elevate CEA and CA 19-9, and peritoneal metastasis could lead to an elevation in CA 125.
Do Not Miss Diagnoses
- Pseudomyxoma Peritonei: A rare condition characterized by recurrent mucinous ascites causing abdominal distension. It often arises from a low-grade mucinous neoplasm of the appendix. While not typically associated with high levels of these tumor markers, the clinical presentation and potential for misdiagnosis as a more common malignancy make it a "do not miss" diagnosis.
- Primary Peritoneal Cancer: Similar to ovarian cancer but arises from the peritoneum itself. It can present with elevated CA 125 and, less commonly, elevated CEA and CA 19-9.
Rare Diagnoses
- Intra-abdominal Desmoplastic Small Round Cell Tumor: A rare and aggressive tumor that can present with elevated tumor markers, including CA 125, and often involves the peritoneum.
- Metastatic Cancer from an Unknown Primary: In some cases, the primary site of the cancer is not identified, and the presentation is with metastatic disease, which could involve the peritoneum and elevate these tumor markers.